I just bought my second 91 Coupe Deville Spring time and I filled her yesterday with 91 0ctane Sunoco. Now when I give it the gas I get the pinging like I used cheap gas. Could it just been a load of bad gas or is there something else that can cause this sensation?:hmm:

I'd start by checking the base timing and the EGR valve.

Thanks I will do that. When you say base timing is that the same as timing the engine, what we used to do in the old days?

Kinda. I forget exactly how on the 4.9 so hopefully some one will chime in but if I remember correctly you have to unplug a green connector at the distributor to disconnect the PCM inputs, then set the base timing (like the old days). Wait for someone to confirm this if you don't have a service manual.

I think you have to jump terminals A & B on that connector under the dash. That will set it to timming mode. Once there get ur light out and a 15mm wrench. Loosen the distrb. hold down bolt. Search on it under the HT4100/4.9 section. Should be 10* BTC. Unless "base timing" is something else. If it is then wat is it?

also note alot of pings and knocks can be caused simply by low oil levels

If you are getting knocking because of low oil levels, you have bigger problems to worry about.